Objectives: To evaluate the clinical outcomes following the use of goserelin and suction curettage prior to ThermaChoice II balloon endometrial ablation to treat menorrhagia. Methods: Qualified patients (n = 105) were randomized to receive either goserelin 3.6 mg one month before or suction curettage immediately before undergoing thermal balloon endometrial ablation. All patients had negative Papanicolaou smears, normal endometrial histology, and normal findings on transvaginal sonography. Uterine bleeding was documented by menstrual diary scores at baseline (Higham score > 150), and at three, six, and 12 months after the procedure. Five patients withdrew prior to surgery and 50 patients were anaesthetized in each group. Two patients in the suction curettage group had their management converted to hysteroscopic ablation, one because of a large uterine cavity (> 12 mL) and one because of a submucous myoma. The ThermaChoice II system circulated the liquid within the silicone balloon for eight minutes at approximately 180 mmHg pressure and 87°C. Results: Participants' mean age, weight, and duration of menorrhagia were not significantly different between the groups. No safety issues related to the device were noted. At one year after ablation, the median reduction in Higham score was from 286 to 10 (96.5%) in the goserelin group (n = 47), and from 272 to 14 (94.9%) in the curettage group (n = 45). The combined amenorrhea/hypomenorrhea rates (higham score 0 to 35), eumenorrhea rate (higham score 36 to 75) and menorrhagia rate (higham score > 75) were 85%, 9%, and 6% (goserelin), and 76%, 16%, 9% (curettage), respectively. Patients' reported self-assessment of dysmenorrhea was none (51%), mild (30%), moderate (10%), and severe (9%) in both groups. Patient satisfaction was 89% in the goserelin group and 95% in the curettage group. In the goserelin group, one patient had a hysterectomy for bleeding and two had repeat resectoscopic endometrial ablations, one for pain (hematometra) and one for pain and bleeding. In the curettage group, one patient had repeat resectoscopic ablation, one patient withdrew, and one requested hormone therapy. The overall success rates were 88% in the goserelin group and 89% in the curettage group. Conclusion: At one year after ThermaChoice II treatment, 88.5% of women had normal menstrual bleeding or less. There was a non-significant trend (a lower Higham score) towards superiority of goserelin therapy before ablation compared with curettage.